On Fri, 12 Jul 2013 12:44:28 -0400 (EDT) Daniel Drake <dsd at laptop.org> wrote:
> Hi, > > Based on the outcomes of the "Best practice device tree design for display > subsystems" discussion I have drafted a DT binding. Comments much appreciated. > > At a high level, it uses a "super node" as something for the driver to bind > to, needed because there is no clear one device that controls all the > others, and also to distinguish between the Armada 510 possible use cases > of having one video card with two outputs, or two independent video cards. > It uses node-to-node linking beyond that point, V4L2 style. > > I have some questions still: > > 1. What names does the Armada 510 datasheet give to the components? Below > I renamed the "LCD controllers" (which don't control LCDs on any of the > current target hardware) to "display controllers". For what we were > previously referring to as DCON, I renamed to "output selector". I would > like to match the docs. > > Actually the output selector is not mentioned as per Sebastian's > suggestion, but I believe it would fit in the below design once the first > user comes along (e.g. it would slot in the graph between dcon0 and > tda99x). > > 2. On that topic, what names does the Armada 510 datasheet give to the > available clocks? Lets make them match the docs. > > 3. What is the "remote" property in the video interfaces binding? Doesn't > seem to be documented. But I think I copied its usage style below. Hi Daniel, The Armada 510 spec is: http://www.marvell.com/application-processors/armada-500/assets/Armada-510-Functional-Spec.pdf > Marvell Armada Display Subsystem > > Design considerations > --------------------- > > The display device that emerges from this subsystem is quite heavily > componentized and the formation of the composite device will vary by SoC and > by board. The DT binding is designed with this flexibility in mind. > > For example, there are 2 display controllers on the Armada 510. > They could legitametely be used to form two independent video cards, or > they could be combined into a single video card with two outputs, depending > on board wiring and use case. > > As there is no clear component that controls the other components, especially > when we wish to combine the two display controllers into one virtual device, > we > define a top-level "super node" that describes the basic composition of the > overall display device. That node uses phandles to define the start of the > graph of display components. > > In the bindings for the individual display components, phandle properties > are used to represent direct, fixed links to other components. We use the > port/endpoint abstraction from bindings/media/video-interfaces.txt to > represent these links. > > > display super node > ------------------ > > Required properties: > - compatible: "marvell,armada-display" > - marvell,video-devices : List of phandles to the display controllers that > form this composite device. > > Optional properties; > - reg: Memory address and size of a RAM allocation designated as graphics > memory > - linux,video-memory-size: If reg is not provided, this property defines > how much memory to cut out of regular available RAM to be used as graphics > memory. > > > display-controller node > ----------------------- > > Required properties: > - compatible: "marvell,armada-510-display", "marvell,mmp2-display" or > "marvell,mmp3-display" > - reg: Register space for this display controller > - clocks: List of clocks available to this device. From common clock binding. > - clock-names: Names of the given clocks (see below) > - ports: From video interface binding > > Valid clock names for Armada 510: extclk0 extclk1 axi pll > > Valid clock names for MMP2: lcd1 lcd2 axi hdmi > > Valid clock names for MMP3: lcd1 lcd2 axi hdmi dsi lvds > > > Example: > > display { > ?? ?? compatible = "marvell,armada-display"; > ?? ?? ?? reg = <0 0x3f000000 0x1000000>; /* video-mem hole */ > ?? ?? ?? marvell,video-devices = <&dcon0>; > ?? ?? }; > > dcon0: display-controller at 20000 { > compatible = "marvell,armada-510-display-controller"; > ?? ?? ?? reg = <0x20000 0x1000>; > ?? ?? ?? interrupts = <47>; > ?? ?? ?? clocks = <&ext_clk0>; > ?? ?? ?? clock-names = "extclk0"; > > port { > dcon0_1: endpoint { > remote = <&tda998x>; > }; > }; > }; > > &i2c0 { > ?? ?? tda998x: hdmi-transmitter at 60 { > ?? ?? ?? compatible = "nxp,tda19988"; > ?? ?? ?? ?? reg = <0x60>; > port { > tda998x_1: endpoint { > remote-endpoint = <&dcon0_1>; > }; > }; > ?? ?? ?? }; > }; Some remarks: - I think it is better to keep the names 'lcd' for the memory to dumb panel sub-devices and 'dcon' for the dumb panel to LCD/VGA sub-device, as named in the spec. - the phandles to the clocks does not tell how the clock may be set by the driver (it is an array index in the 510). - I don't see the use of the phandles in the leaves (dcon and tda998x). Well, here is how I feel the DTs: - for the Cubox (one LCD, the DCON is not used, TDA998x for HDMI/DVI output): video { compatible = "marvell,armada-video"; marvell,video-devices = <&lcd0> /* only one device */ }; /* the LCD reg and interrupts are described in dove.dtsi */ &lcd0 { status = "okay"; clocks = <&core_clk 3>, <&lcdclk>, <&si5351 0>; marvell,clock-type = <0>, <2>, <3>; /* how to set the clock */ marvell,connector-type = <11>; /* HDMIA */ marvell,external-encoder = <&tda998x>; }; &i2c0 { si5351: clock-generator { ... }; tda998x: hdmi-encoder { compatible = "nxp,tda998x"; reg = <0x70>; interrupt-parent = <&gpio0>; interrupts = <27 2>; /* falling edge */ }; }; - for some tablet based on the Armada 510 with a LCD and a VGA connector: video { compatible = "marvell,armada-video"; marvell,video-devices = <&lcd0>, <&lcd1>, <&dcon> }; /* the LCDs reg and interrupts are described in dove.dtsi */ &lcd0 { /* LCD */ status = "okay"; clocks = <&lcdclk>; /* only the LCD clock */ marvell,clock-type = <2>; marvell,connector-type = <7>; /* LVDS */ display-timings { mode { hactive = <1920>; vactive = <1080>; hfront-porch = <88>; hsync-len = <44>; hback-porch = <148>; vfront-porch = <4>; vsync-len = <5>; vback-porch = <36>; clock = <148500>; }; }; }; &lcd1 { /* VGA */ status = "okay"; clocks = <&core_clk 3>, <&lcdclk>; /* only the AXI and LCD clocks */ marvell,clock-type = <0>, <2>; /* how to set the clock */ marvell,port-type = <1>; /* VGA */ /* there may be some external encoder to handle DAC */ }; /* the DCON reg and interrupts are described in dove.dtsi */ &dcon { status = "okay"; }; -- Ken ar c'henta? | ** Breizh ha Linux atav! ** Jef | http://moinejf.free.fr/
